15 May 2003
DESSICANT DEHUMIDIFICATION. Both the ASHRAE Handbook
Fundamentals and Handbook Applications describe several applications where
desiccant dehumidification should be considered. These applications include instances
where the latent load is large in comparison to the sensible load and instances where
the energy costs to regenerate the desiccant is low relative to the energy costs required
to dehumidify the air by chilling it below its dewpoint.
THERMAL ENERGY STORAGE. Consider using thermal energy storage
(TES) where, for example, it could reduce peak power demand charges, provide
additional cooling capacity where it is more life cycle cost effective than adding cooling
equipment, or provide life cycle cost effective redundancy necessary to ensure reliability
for critical applications. The hourly cooling load for the facility along with the hourly
power consumption of the installation must be determined in order to design TES.
Ensure that the supply water from the storage tank is at or below the required entering
water temperature of all cooling coils during the last hour that the TES will be used at
the outdoor design conditions specified. Where "ice-on-coil" is used as the method for
TES, the loss in efficiency that occurs when chilling water to a lower design temperature
must be factored into the life cycle cost analysis. This loss in efficiency may be
somewhat offset by the lower temperature of the air entering the condenser during the
hours when the system is "recharging." For facilities where a water tank is required, it
may be advantageous to specify a tank suitable for storing chilled water.